In certain markets, data centers employ various rack-mounted systems contained within an enclosure that mounts to a preconfigured frame, such as a US standard 19″ or 23″ rack. The 19-inch (48.26 cm) or 23-inch (58.42 cm) dimension refers to the width of the equipment mounting frame in the rack, i.e. the width of the equipment that can be mounted inside the rack. A rack unit, U or RU, is a unit of measure used to describe the height of equipment intended for mounting in these racks. One rack unit is 1.75 inches (44.45 mm) high. These systems have an excellent functional density envelope. Their user interface is in the front and their wiring interface can be in the front or the back. Once the subsystems are installed in the field, there is little reason to move them and the wiring in the back can be left closed to public access.
One element often included in rack mounted data center systems is a surge protection system. For surge protective devices (SPDs) that mount in a rack system, there is little need for functional interface or wiring in comparison to the size of the individual SPD devices. The enclosure can be dense inside with a small cross section in the rack. While SPDs can provide years of service without failure, they do eventually wear out or may need to be serviced after a surge event. In those situations, the typical system needs to be replaced by disconnecting all wires or removing internal subassemblies. These approaches may require the larger data center system to be shut down or left unprotected during service.
In rack mount environments, standard equipment practice has become the use of a surge protection system that contains multiple SPDs using an enclosure that is two RU high and offering twelve remote radio head (RRH) protection. In one approach, replacement or service of the SPDs includes pulling a drawer out of the rack mount enclosure to give access to the parts. This is complicated and presents multiple places and modes for failure.
Alternatively, certain commercially available surge protection solutions are DIN rail mounted and pluggable. Pluggable DIN rail SPDs can be mounted in the front panel of the enclosure where they can be repaired without removing anything except the failed device. This has many benefits including ease of mounting, flexibility and user reparability without unwiring. For permanent installations and control cabinets, this design is well suited where the DIN rail can be screwed to the back-plate and there is ample room to manage wiring around it.
However, the use of current DIN rail mounted pluggable surge protection in rack mount applications has heretofore been somewhat unsatisfactory in light of shortcomings as it relates to their ability to be used in conjunction with what has become the standard equipment practice for rack mount applications as previously described (i.e. 2 RU, 12 RRH).
A typical DIN rail SPD base requires substantial space to the sides for wiring which limits device density. DIN rail assemblies that are not directly on the back plate also require supplementary support structure to mount the DIN rail. This can further obstruct wiring channels and add cost. As a result of these space requirements, the ability to provide 12 RRH protection in conjunction with pluggable SPD protection has generally been limited to units having a height of 3 RU or higher; alternatively, known efforts to meet a 2 RU height has heretofore been limited to 6 RRH protection (see FIG. 1). In each case, a significant mechanical stress is still placed on the connecting wires, which are bent at an approximately right angle as they leave the enclosure and enter into the base element (see FIG. 2).
The function of an SPD is to give a path to ground for high-energy overvoltages. These can couple to adjacent conductors when laid across one another. Remote function indication circuits available on some devices can be used, but connecting them around the conductors that are being surge protected offers a place for a surge to couple to an unprotected conductor that is part of the function monitoring circuit.
A rack mount system with improvements in the process and/or the properties of the components formed would be desirable in the art.